1. Field of the Invention
The present invention relates to systems utilizing redundancy switchover control. More particularly, the present invention relates to redundant-type systems, such as a redundant-modem system, including similar independent components at least one of which monitors the others and serves as a spare component.
2. Discussion of the Related Art
In systems that require a high degree of reliability, such as redundant stand-alone satellite modem systems or redundant telephone switches, redundant components are often added to serve as a backup or spare component. Redundant stand-alone satellite modem systems typically include spare modems provided to replace a modem when it fails so as to not interrupt communications.
Generally, when a system includes a spare component, separate switches, as well as redundancy switchover control equipment, must be connected to the system. Typically, a redundancy switchover controller monitors the status of an operating component and controls switches connected to the inputs and outputs of the operating component and the spare component such that the spare component may effectively replace the operating component when a failure occurs.
To accomplish its tasks, the redundancy switchover controller and the associated switches require a multitude of connectors. From a practical standpoint, the more connectors the system requires, the more expensive the system becomes and the harder the process of connection becomes. Numerous connectors become particularly burdensome when one must replace a component, and especially burdensome should the redundancy switchover controller require replacement. Moreover, more connectors translate into more sources of possible failures.
In an effort to reduce the number of connections, some redundancy switchover controllers are housed within the same housing module as the spare component. This way, the manufacturer may make some of the required connections internally within this housing. Such an arrangement is disadvantageous in that the cost of replacing a failed spare component is higher due to the fact that it shares a housing with the redundancy switchover controller. Moreover, when the spare component requires replacement, one may have to disconnect the redundancy switchover controller from both the spare component and the other operating components. Thus, this arrangement presents a major inconvenience should the spare component fail.
Conventional redundancy switchover controllers typically include their own processors and power sources. Not only do such processors and power sources significantly add to the cost of the system, they also constitute sources of possible failure.